This page in a nutshell: Do not add content to Wikipedia if you think that doing so may be a copyright violation. Contributors should take steps to remove any copyright violations that they find.

One of the most important aspects of Wikipedia is that its text (not media; but that will be discussed shortly) may be freely redistributed, reused and built upon by anyone, under the terms of the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC BY-SA) and, except where otherwise noted, the GNU Free Documentation License (GFDL) (unversioned, with no invariant sections, front-cover texts, or back-cover texts). Contributors agree to release their original content under both licenses when they submit it, and material from public domain sources or other compatibly licensed sources may also be used in accordance with the copyright policy, provided correct attribution is given.

However, copying material without the permission of the copyright holder from sources that are not public domain or compatibly licensed (unless it's a brief quotation used in accordance with Wikipedia's non-free content policy and guideline) is likely to be a copyright violation. Even inserting text copied with some changes can be a copyright violation if there is substantial linguistic similarity in creative language or sentence structure; this is known as close paraphrasing, which can also raise concerns about plagiarism. Such a situation should be treated seriously, as copyright violations not only harm Wikipedia's redistributability, but also create legal issues.

Dealing with copyright violations

Handling of suspected violations of copyright policy depends on the particulars of a given case. If you suspect a copyright violation but are uncertain if the content is copyrighted or whether the external site is copying from Wikipedia, you should at least bring up the issue on that page's discussion page, if it is active. In that case, please tag the page {{copypaste|url=insert URL here, if known}}, unless your concerns are swiftly resolved. Others can then examine the situation and take action if needed. The most helpful piece of information you can provide is a URL or other reference to what you believe may be the source of the text. You may also make a note of your concerns at Wikipedia:Copyright problems.

Some cases will be false alarms. For example, text that can be found elsewhere on the Web that was in fact copied from Wikipedia in the first place is not a copyright violation – at least not on Wikipedia's part. In these cases, it is a good idea to make a note of the situation on the discussion page. Also, if the contributor is the copyright holder of the text, even if it is published elsewhere under different terms, they have the right to post it here under CC BY-SA and GFDL without violating copyright, so long as they provide a suitable release to the world under Wikipedia's licenses or a free license that is compatible with them. (Text may, however, still be unsuitable for Wikipedia for another reason.) A copyright holder cannot both retain non-free copyright elsewhere over their content, and license it for one-time use here with their permission, because Wikipedia's licensing scheme requires that its readers and end users be able to reuse the content under the free license notice that is posted at the bottom of every page. The procedures for donation of non-free copyrighted material by its release is described at Wikipedia:Donating copyrighted materials. Until the donation process is complete the article should be replaced with {{subst:copyvio|url=insert URL here}}. Similarly, if they can verify compatible license through a notice at the external site or can prove that the content is public domain, this is not a copyright violation. A note explaining the situation should be made on the talk page (including, if there is a release, the URL of where the release can be found; permission conveyed through e-mail must be confirmed through the procedure at Wikipedia:Requesting copyright permission) and proper attribution given on the article's face. See guidance on attribution for sources under copyleft or released into public domain.

If you have strong reason to suspect a violation of copyright policy and some, but not all, of the content of a page appears to be a copyright infringement, then the infringing content should be removed with the source url in the edit summary if possible. Revision deletion should then be requested by placing {{copyvio-revdel}} on the article page or directly contacting an administrator on their talk page. Administrators may at their discretion unilaterally revision delete copyrighted content. A note explaining the removal may also be made on the discussion page, along with the original source, if known. {{subst:cclean|url=insert URL or description of source here (optional)}} has been created for this. If the copyright holder's permission is later obtained, the text may be restored. If all of the content of a page appears to be a copyright infringement or removing the problem text is not an option because it would render the article unreadable, check the page history; if an older non-infringing version of the page exists, you should revert the page to that version. A revert that only removes infringing material does not violate the three-revert rule.

If there is no such older version, you may be able to re-write the page from scratch, but failing that, the page will normally need to be deleted. In limited circumstances, administrators may delete obvious copyright violations on sight; see the relevant section of the speedy deletion policy. Contributors may list pages that meet these conditions for deletion using the {{db-copyvio}} template.

If the criteria for speedy deletion do not apply, and you believe that there are reasons that the text should be rewritten instead of removed, you should blank the article or the appropriate section with the {{subst:copyvio|url=insert URL here}} template, and list the page at Wikipedia:Copyright problems; see instructions. This will give interested contributors a week to verify permission for the text or propose a rewrite. If, after a week, the page still appears to be a copyright infringement and no usable rewrite is proposed, it may be deleted by any administrator or reduced to a non-infringing stub.

Addressing contributors

If you can identify the contributor of the content, please notify them of Wikipedia's Wikimedia:Terms of Use and copyright policies. When an article has been tagged for speedy deletion or masked for copyright investigation, the tag will display a template that can be used for this purpose. You can also use the templates posted at Wikipedia:Template messages/User talk namespace.

Contributors who repeatedly post copyrighted material despite appropriate warning may be blocked from editing by any administrator to prevent further problems. Contributors who have extensively violated copyright policy by uploading many copyrighted files or placing copyrighted text into numerous articles may be blocked without warning for the protection of the project. These blocks are usually indefinite, pending satisfactory assurances that infringement will not continue. In extreme cases administrators may impose conditions before unblocking, such as helping with cleanup by disclosing the sources they used. If contributors have been shown to have a history of extensive copyright violation, it may be assumed that all of their major contributions are likely to be copyright violations, and they may be removed indiscriminately. See Wikipedia:Contributor copyright investigations.

Information for copyright owners

If you are a copyright owner or represent a copyright owner, and you believe that Wikipedia is infringing your copyright, we can assist you best via e-mail. You may contact info-en-cwikimedia.org with an informal request; please cite the exact URL (the "address" or "location" of the page as shown by your web browser, beginning with https://en.wikipedia.org/...), and provide enough information to substantiate your claim of copyright ownership. Be aware that correspondence is answered by a small number of volunteers, and an immediate reply may not be possible.

Duplication Detector - A tool used to compare any two web pages to identify text which has been copied from one to the other. Either, neither, or both pages may be current or old revisions of a Wikipedia article.

CopyPatrol - A tool which analyses every new edit for copyright violation and shows an easy comparison view for cross-checking the copyright violation. It is a work-in-progress at the moment.